What is the equation for the line ?

The function a represents the cost of manufacturing product a, in hundreds of dollars, and the function b represents the cost of manufacturing product b, in hundreds of dollars. a(t) = 5t + 2 b(t) = 7t - 2t +4 find the expression that describes the total cost of manufacturing both products, a(t) + b(t). a. 7t^2 - 7t + 2 b. 7t^2 + 3 +6 c. 7t^2 + 7t - 6 d. 7t^2 - 3t + 6

Add the fractions, and simply the result to lowest terms. 2/3 + 2/7= ?

Which of the following would be a good name for the function that takes the weight of a box and returns the energy needed to lift it?